Arco: new bass amps from Danmark

Mathias has sent me a review of the new Arco “Hugo” double bass amp, which is made by bassist Jesper Lundgaard. It’s to long to fit the proper comment field, so I descided to post it here. Here we go:

The arco-amplification Hugo

Arco Amplification is a brand name owned by Jesper Lundgaard, who has been developing amplifiers since his early youth. Looking back on an amazing career as a touring musician, he decided to take it a bit easier, stay home more, and focus on building bass and guitar amplifiers. He used to work together with a company named CADaudio, but they split and now he’s a one man company. It’s likely his company name will change in the future, but for now, it’s arco amplification.
The “hugo” is an amp built according to suggestions of Hugo Rasmussen, another legendary danish bassist. This is the amp I had the pleasure to try for a couple of days.
The long-bearded legend seems to be a sucker for simplicity- the amplifier sports a very stripped down set of controls. From left to right, they are: Master Volume, a mute switch, treble and bass controls, a phase reverse switch, and a tone switch (where you can change between bright, normal, and dark). The amp has two inputs named “lo-z” and “hi-z”, and on the back there are two speaker outputs (one neutrik-speakon and one ¼” jack), a DI out and a mains cable plug which can be changed to a permanently attached mains cable if the customer wishes. The 500W power amplifier drives an 8 ohm, 8 inch neodym-speaker and comes to its full power potential when you hook up another enclosure to reach 4 ohm.
The speaker connectors seem a little peculiar at first. There are both a jack and a speakon, and the jack plug disconnects the internal speaker (in case you want to connect a 4 ohm enclosure), while the speakon doesn’t. Jesper said this is to give the user an option without an extra switch, and that seems reasonable, even though it´s a slightly unusual design decision. And it forces the user into using a speakon-to-jack cable in certain situations, but that’s no big deal.
Remarkably small is the first thing that comes to mind when you see the amp. Pictures on the web give no realistic impression, but if you´re at your desk, you most likely have a DIN A4 paper around- add just about 5cm with and length, and you have the dimensions  of the front. That’s pretty darn small, I have to say, and once you lift it for the first time, you notice the extremely light weight- it weighs 7,9 kilos, making it the lightest bass combo around. The power/weight ratio is just stunning. To achieve this, the absence of a traditional power supply is a big factor. Instead, the arco amplifiers have switching power supplies.
While the power supply is rather modern, the wiring is rather traditional, and that’s a good thing: Instead of being soldered directly into the PCB, the pots are wired to the circuit board just like in old times. This saves the board from being damaged when mechanical shock occurs. The integrated circuits are socketed where possible, so that if one component fails, you can easily service the hugo.
Yesyes, but the sound? I tried it at home first, and while that does not say much, it sounded outstanding. Very neutral, very clear, very strong. Very promising of the gig I played with it. Here, it was almost magic. The playing situation was far from ideal, being in a corner like often, the amp served almost only as a bass monitor for the drummer. But in this function, it was great also. It gave me a strong confident feeling to just hear my instrument as it sounds without an amp, but with more power and volume. There were no amplified characteristics in the sound. I believe that the microphone-like pickup (Schertler dyn-b) I use plays a big part in this, but there are may amplifiers out there that sound horrible with this pickup. It’s supposed to be connected to a PA or an active speaker. That means, it calls for a super-neutral flat response amplifier, and that’s what the arco is.
On a rehearsal the next day, the pleasure continued. Trio with piano and drums, in a wonderful room, and the bass sound was… just this. The bass sound. Without any artificial colorings.
In all this, I barely used the tone controls. I almost only did for test purposes, and that’s what I found: The bass control has enormous power and can fatten the sound to a degree you’ll likely never use, yet it’s fine enough to just add a little if your bass, the room, or your taste calls for more fatness.  The treble control acted weird, as it was, at least in my setup, more a midrange honk control. Turning it up didn’t add any transparency, just nasal mids, turning it down made the sound kind of undefined über-hifi. I asked Jesper about this (being a disappointment that doesn’t fit the great impression the amp made), and he said the effect was due to this amp being a prototype, and the treble frequency was due to change in any case. Plus, he offered to try different frequencies that fit my pickup best.
The tone switch proved very effective, and I used it to adjust the sound according to the volume. Playing softer, I chose the bright position, and turing it up (to a level I never use, I have to say), the now a little harsh sound (due to the frequency of the treble control, which was turned a notch over neutral) could be tamed and naturalized by using either medium or dark.
The phase switch is a very effective tool against boomy feedbacks in situations where you cannot move sufficiently. It’s found on some amps already and I firmly believe this should be a feature for every amplifier that´s intended for double bass use. (The Schertler dyn-b has its own phase switch, but it’s located quite uncomfortably at the jack, and I much prefer futzing at  the amplifier in a gig situation).
And the mute switch is very valuable in set breaks, as it’s the most direct way of silencing the system without any potential clicks (of the power switch) and changes in volume.
The playing experience was such a pleasurable one that I have a hard time going back to my Acoustic Image amplifier. Those two just don’t compare in neutrality and power, the arco is way cleaner and a lot louder and just works better for what I want. The AI sound is kind of midrangey, and for some pickups (obviously, as it’s so popular, for many) it does work quite well, but I always had honk problems and nasalities with it that I had to eq out to be kind of happy. With the arco, it´s just “plug and play” and you have a great sound from second one.
The price of €1600 is quite high, but I think it’s justified by the fact that Jesper only builds to order, so there’s never a big stock of parts. And he builds them all alone and by hand, so the price is okay.  And the everyday ease of carrying an amplifier that’s lighter than anything else on the market is just wonderful and worth the money already.

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10 thoughts on “Arco: new bass amps from Danmark

  1. Pingback: Arco: new bass amps from Danmark | Double Bass Guide | High technology information

  2. Johannes

    Interesting review, especially due to the fact that the arco amp is compared with the acoustic image amp. However, I’m not sure if such a traditional amp with front speaker would convince me since I like the downfiring speaker concept of the AI very much. With the AI it feels like playing a bass with a huge body, not like playing bass and hearing yourself from behind or aside through a speaker. I would also like to know if Mathias has heard this amp from the distance (played by another bassist).
    Finally, it would be interesting how this amp performs with traditional piezo pickups. The 2.5 MOhm “high” impedance input might be a bit too less (the AI has 10 MOhm)…

  3. Mathias



    I´m positive about the principle of the downfiring speaker also, I have played AI for years and always liked that aspect of it. However, if I have to choose between a VERY natrual sounding frontfiring speaker and the AI, I´ll choose the first, since that was what I always disliked about the AI most- the strong honky midrange that you sometimes can´t even tame properly with the built-in eq. I had that, to different degrees, with all the pickups I tried (b-band, realist, underwood, dyn-b). I never understood why they built such a fine and flat sounding amp when they combine it with a cabinet that sends all flatness down the drain in favor of an almost telephone-sharp sound. Okay, slightly exaggerated, but you know what I mean.I ALWAYS turn the mids anywhere between 3/4 down and all the way down on the Contra.
    The diffusing effect of the downfiring speaker has its disadvantages for me also- sometimes I have trouble spotting me in the stage sound, to the point where I really dislike the overall feel while trusty audience members enjoy it. I mean, it’s cool they like it, but I have to like it, too.
    I have unfortunately not heard the hugo from a distance when somebody else played it, but in the rehearsal room I used a ridiculously long cord and had the amplifier in its normal position while I moved away (like, 8 meters). Not the same (since you always get a little of the bass itself this way), but it sounded very good too.
    I played it on Jesper’s basses (eminence and some kind of doublebass) with a Realist, and while I’m not too fond of the Realist, it worked quite well. I believe that Walter Woods’ amps have 1MOhm impedance and they work very ok with your average piezo…

  4. Jonas Post author

    @Johannes: “The higher the input impedance, the better the sound”: this is not true for all pickups. I’ve a small testing device which does no pre-amplification, but only changes the input impedance from 1 MOhm to 10 MOhm in steps of 1 or 1,5 MOhm. I’ve tested a couple of pickups, and they all didn’t sound best at 10 MOhm (too much boomy bass in most cases). The optimum input impedance level was different for every pickup. And in most cases, I liked something around 2 to 4 MOhm best.
    BTW: The new Headway EDB-1 preamp has a switchable (3 way) input impedance. I think it’s the only device on the market with this feauture. I usually don’t use the highest impedance with the EDB-1, too.

  5. Mads Vinding

    I have the larger B510 model and this is the best amp I have ever used – and I think I tried them all!
    It has so many useful features and the sound is big, pure and powerful. It has enough power to drive a bigband and the small weight and dimensions makes it easy to travel with.
    The 4 EQ’s are perfect and the line output is better than anything I ever heard.
    It gets my full recommandation!

  6. Peter Wilson

    Hi Jonas,

    One thing that is hard to understand: My CAD Ebass DB 510 cost 920 Euros; that’s the version of this same amp design, but with all the EQ and switches. Jesper’s Hugo version — with most of the controls ommitted — cost 1600 Euros??! Ouch.

    Best wishes,

    – Peter Wilson

  7. Mathias

    @Peter Wilson


    I’m neither going to join any mudfights between a company and an ex-developer (Jesper collaborated with CADaudio on their amp designs) who separated from each other, nor am I going to fuel these fights with ammunition. I don’t know if it is the same amp, I only know that Jesper claims it’s been redesigned, different players have compared their DB510 to Jespers B510 model and they stated Jesper’s is a totally different animal. Jesper’s prices ar e his choice (reflecting the fact that he’s a one-man-company and the amps far from serial production), if you like the amp and you can pay the price, fine, if not, fine as well.

    Plus, I don’t know if you can correlate the number of controls to price. If a given feature set is what one wants, fine. This amp is designed to Hugo Rasmussen’s wishes, so he’s likely very happy with the “omitted” controls.

  8. Alex Richardson

    Thanks Jonas for your intesteng comments regarding input/output inpedance.
    Its a fact that maximum power transfer occurs when the input and output impedances are the same, maybe that’s why you found the switchable impedances so good.
    All the best Alex.

  9. Michael Edinger

    re Alex and impedance

    you´re right of course from a tech point of view, but more is at stake here:
    in General the Piezo pickup´s impedance has a strong capacitive component plus untold mechanical resonances and phase issues, that all contribute to the unpredictability of the resulting sound with different amplifiers internal input impedances and capacitances-
    So the sound character and the frequency response is really a matter of trying again and again.


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